Burr removal apparatus

ABSTRACT

Apparatus for removing a burr from an aperture in a workpiece, using a rotating deburring tool having a flexible or partly flexible shaft, an abrasive mechanism that rotates on the shaft and a collar that protects the workpiece from abrasion when the abrasive mechanism is being positioned for deburring. Optionally, the shaft and abrasive mechanism move laterally as they rotate. Optionally, a shaft holder includes a protective surrounding sleeve to catch or deflect any fragment of the shaft holder that might fly off. Optionally, the shaft and the workpiece rotate independently of each other. Two or more different abrasive mechanisms can be simultaneously attached to the shaft. The cross-sectional shape of the abrasive mechanism may be curvilinear and/or polygonal, depending upon shape of the workpiece surface. Optionally, a shaft restrictor receives the shaft and limits lateral motion of the rotating shaft. The shaft optionally includes a rotatable mass that provides additional rotational inertia after the shaft is initially spun up.

FIELD OF THE INVENTION

This application claims priority based on a Provisional Application,Serial No. 60-214,829, filed on 28 Jun. 2000 by the inventor namedherein and entitled “BURR REMOVAL APPARATUS.” This invention relates toremoval of burrs and similar unwanted projections from metals and otherrelatively hard materials.

BACKGROUND OF THE INVENTION

Removal of undesirable projections (collectively referred to as “burrs”herein) from a surface, such as a metal or other relatively hardmaterial, is important in the metal finishing industry, especially wherepresence of an unremoved burr can interfere with flow of a liquid orwith the positioning of electrical charge-carrying lines. Producers ofvehicles, such as automotive vehicles, water-borne vehicles and aircraftare especially concerned with burr removal on surfaces of tubes,cylinders and other containers and housings.

However, many of the surfaces that contain burrs (referred to herein as“burred surfaces”) are relatively inaccessible, located in small spacesand cannot be de-burred by a conventional de-burring tool. For example,when two intersecting vias or apertures are drilled in a metal,breakthough of the drill for the second aperture into the space that ispart of the first aperture will often produce a large metal burr at ornear the intersection.

Further, in some situations two or different burr removal materials maybe needed within a single container or housing. One example occurs whererough burr removal is to be followed by finishing, each requiring adifferent burr removal material or tool shape. Another example occurswhen a container includes two or more different materials, each with aburred surface that requires its own burr removal mechanism andassociated material.

When a burr removal tool is positioned to remove a burr, operation ofthe tool may unintentionally, and undesirably, contact and removematerial that is preferably left intact. A burr removal tool often has aconnecting rod extending between an abrasive nodule used for burrremoval and a motor that provides mechanical movement of the nodule.Occasionally, the nodule briefly binds against the material to beremoved, causing the rod to move laterally or in another uncontrollablemanner.

What is needed is a burr removal tool that is flexible for reachingaround obstructions and corners, can fit into relatively small spaces,provides two or more different burr removal materials in a single tool,and provides protection of a burred surface as the tool is moved intoposition for burr removal. Preferably, the tool should be small andflexible enough to permit rapid interchange of one type of burr removalmechanism by another. Preferably, the shape of the burr removal noduleshould be chosen to minimize the amount of non-burr material that isremoved. Preferably, motion of the shaft should be controlled to preventoccurrence of undesired excursions when the burr removal noduletemporarily binds against material being removed.

SUMMARY OF THE INVENTION

These needs are met by the invention, which provides apparatus havingone, two or more different abrasive mechanisms, attached to a rotatableshaft and having one or more non-abrasive collars thereon in oneembodiment. An approximately cylindrically symmetric abrasive mechanism,including an exposed abrasive material (preferably with Mohs hardness atleast about 5.5), is attached to a rotatable shaft, and a collar ofrelatively non-abrasive material (prefereably with Mohs hardness muchlees than 5.5) is attached to the shaft and/or to the abrasive mechanismadjacent to the abrasive mechanism. The shaft is optionally flexible andcan be bent or deformed or tilted as the shaft rotates to expose aportion of the abrasive material to remove one or more exposed burrs.Presence of the non-abrasive collar allows the shaft to be moved intoposition and applied for burr removal at one location on a surfacewithout scoring or otherwise abrading another portion of the surface.Optionally, the workpiece including the burred surface may rotateinstead of, or independently of, the rotating shaft. without scoring orotherwise abrading another portion of the surface. Optionally, theworkpiece including the burred surface may rotate instead of, orindependently of, the rotating shaft.

Optionally, the cross-sectional shape of the burr removal nodule ischosen to be ovular, quadrilateral, trapezoidal or polygonal to minimizeundesirable removal of adjacent material. Optionally, a shaft restrictoris provided to control or prevent lateral excursions of the shaft in onedirection.

In another embodiment, two or more approximately cylindrically symmetricabrasive mechanisms are separated by a space or by a non-abrasive collarand are attached to a rotatable shaft. Optionally, each of the abrasivemechanisms includes a different abrasive material so that the burrremoval apparatus can be applied to different surfaces or materialswithout removing the burr removal apparatus to change from one abrasivematerial to another. A flexible shaft may include a flexible spring as aportion of the shaft, Alternatively, a shaft may be attached or rootedat one end thereof to a flexible material, such as rubber, that allowsthe direction of the shaft to be varied by applying force to one side ofthe shaft to force the shaft against the workpiece surface.Alternatively, one or more small abrasive nodules, each attached to ashaft by a transversely extending rod, may be rotated with the shaft toremove one or more burrs.

In another embodiment, a shaft restrictor is provided to restrictlateral movement of the shaft in one or more lateral directions, todiscourage the shaft from binding against a work surface being deburred.In another embodiment, the shaft is provided with an additionalrotatable mass that maintains angular velocity of the shaft in thepresence of frictional forces, even where a rotational drive mechanismfor the shaft is turned off.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B, 4A and 4B, 5 and 6 illustrate use of single and multipleabrasive mechanisms as part of the invention.

FIGS. 2 and 3 illustrate flexible shaft configurations that can be usedwith the invention.

FIGS. 7A, 7B, 8A, 8B, 9A and 9B illustrate systems with combinedflexible and inflexible shafts and flexible shaft holders.

FIGS. 10 and 12A-12D illustrate systems in which both shaft andworkpiece rotate.

FIGS. 11A and 11B illustrate a system having two abrasive mechanisms.

FIGS. 13, 14 and 15 illustrate use of a superflexible shaft to drive anabrasive mechanism.

FIGS. 16A and 16B illustrate suitable abrasive mechanism cross-sectionalshapes for use with curvilinear and polygonal corners.

FIGS. 17A and 17B illustrate use of a deburring tool to reshape a comerin a side wall.

FIGS. 18A-18D and 19 illustrate use of types of shaft restrictorsconstructed according to the invention.

FIGS. 20A, 20B and 21 illustrate use of the invention mounted on arotating machine, such as a milling machine or lathe.

DESCRIPTION OF THE INVENTION

FIGS. 1A and 1B illustrate one embodiment of the apparatus 11 in use ina relatively inaccessible space. The apparatus 11 includes a rotatableshaft 13 that is approximately concentrically attached to anapproximately cylindrically symmetric abrasive mechanism 15 that isadjacent to a collar 17 of relatively non-abrasive material, such aswood, plastic, rubber or soft metal (Mohs hardness less than 5.5). Thecollar 17 is attached to the shaft 13 and/or to the abrasive mechanism15 so that the abrasive mechanism and the collar rotate when the shaftis caused to rotate, for example, using a shaft driver (rotator)mechanism 19, such as a motor. In FIG. 1A, when the tool 11 is beingmoved into position in an aperture or opening 24 for deburring one ormore surfaces of a workpiece 21, the workpiece is exposed to the collar17 but is not exposed to the abrasive mechanism 15. This prevents theabrasive mechanism 15 from scoring, gouging or otherwise removingmaterials from one or more surfaces, 23A, 23B and 23C, of the workpiece21. The abrasive mechanism may include one or more materials, such asboron nitride, boron carbide, tungsten carbide and alumina, having aMohs hardness substantially greater than that of most metals (i.e., atleast equal to about 5.5).

The shaft 13 need not be located at the center of the aperture oropening 24 in which the tool operates. The workpiece 21 may be caused torotate about a central axis in the aperture or opening 24, independentlyof whether or not the shaft 13 and abrasive mechanism 15 are rotating.

When the tool 11 has been moved into a desired position, as shown inFIG. 1B, the collar 17 is repositioned or moved aside to expose a burredsurface or other region, such as 23B, to the abrasive mechanism 15 forburr removal. The abrasive mechanism 15 can also be repositioned toremove one or more burrs from another surface, such as 23A, of theworkpiece 21.

The abrasive mechanism 15 need not be approximately cylindricallysymmetric and/or the shaft 13 need not be approximately concentricallyattached to the abrasive mechanism. In this modified configuration, whenthe shaft 13 is rotated, a portion, but not all, of the abrasivemechanism 15 will contact a surface, such as 23A, 23B or 23C, and willremove burrs by contact. This effect can also be achieved by rotatingthe shaft 15 off-center.

The shaft 13 is preferably flexible enough to permit the shaft to bendor flex a modest amount, either as the shaft rotates or as lateral forceis applied to the collar 17 and/or abrasive mechanism 15. FIGS. 2 and 3illustrate two flexible shaft configurations that permit a portion ofthe shaft 13 to bend as the abrasive mechanism 15 or the collar 17 ispressed against a surface of the workpiece. This bending of the shaftallows additional force to be applied in encouraging the abrasivemechanism 15 to contact the portion of the workpiece that is to bedeburred. In FIG. 2, the shaft 13 includes a central cable 13C thatbends modestly as force is applied. In FIG. 3, a portion of the shaftincludes a spring 13S that bends more easily under a lateral force.Other flexible shaft configurations (not shown) include a shaftincluding a portion that is hard rubber and a shaft including awasher/spring.

FIG. 4A illustrates another embodiment 31 of the invention. A shaft 33,preferably flexible, is attached to a first approximately cylindricallysymmetric abrasive mechanism 35A, and the shaft and/or the firstabrasive mechanism is attached or connected to a second approximatelycylindrically symmetric mechanism 35B. The first and second abrasivemechanisms, 35A and 35B, are spaced apart by a groove 39, or by emptyspace if desired. A non-abrasive collar or snap ring 37 is positionedbetween, or adjacent to, the first and second abrasive mechanisms, 35Aand 35B, which may include the same abrasive material or differentabrasive materials, as desired.

If the abrasive materials for the two mechanisms are different, thefirst abrasive mechanism 35A and the second abrasive mechanism 35B maybe used for different purposes on the same container or housing. Forexample, the second abrasive mechanism 35B may be used for rough burrremoval from the surface(s), and the first abrasive mechanism 35A may beused for smoothing and finishing of the same or different surface(s).

In this embodiment, the collar 37 serves another purpose as well, namelyensuring that a surface is exposed to at most one of the two abrasivemechanisms, 35A and 35B, at any one time. The tool 31 may include ashaft drive mechanism (motor or other rotator mechanism) 39 to rotatethe shaft 33.

The lower abrasive mechanism 35B serves another purpose as well. Whenthe tool 31 is being moved into position in an aperture or opening,passage of the tool through the aperture may be blocked by one or moreburrs that extend laterally from a side wall or surface that partlydefines the aperture. When such blockage occurs, the lower abrasivemechanism 35B may be activated to remove, or reduce the size of, theprojection so that the tool can be moved to its desired location withinthe aperture. The upper abrasive mechanism 35A can be used for a similarpurpose.

FIG. 4B illustrates use of the embodiment 31. An abrasive mechanism 35includes first and second approximately cylindrically symmetric abrasivemechanisms, 35A and 35B, and is attached to a shaft 33 driven by a shaftdrive mechanism 39. As the embodiment 31 is inserted into an aperture orhole 36 (or is removed from the aperture or hole), the second abrasivemechanism 35B encounters a first surface 38-1 and removes exposed burrsfrom the first surface. Subsequently, the first abrasive mechanism 35Aencounters a second surface 38-2 and removes exposed burrs from thesecond surface. If only one abrasive mechanism, for example, 35A, isprovided, burrs could not be removed from the first surface 38-1, exceptby removing the embodiment 31 and inserting it into the aperture 36 withthe opposite orientation.

FIG. 5 illustrates another embodiment 41 of the invention, whichincludes a first shaft 43A and a second shaft 43B, with one or both ofthe shafts preferably being flexible and preferably being approximatelyconcentric. Optionally, the first and second shafts, 43A and 43B, areparts of a single, unitary shaft. One or both of the shafts, 43A and43B, is attached or connected to a first abrasive mechanism 45A, whichhas a first non-abrasive collar 47A, and the second shaft 43B isattached or connected to a second abrasive mechanism 45B that iscontiguous to or spaced apart from the first abrasive mechanism 45A andthat has a second non-abrasive collar 47B. The first and second abrasivemechanisms, 45A and 45B, may have the same abrasive materials or mayhave different abrasive materials. The tool 41 may include a motor orother shaft driver mechanism 49 to rotate the shafts 43A and 43B.

FIG. 6 illustrates another embodiment 51 of the invention, in which arotatable shaft 53 is provided with a plurality of laterally orientedrods or projections, 54-1, 54-2 and 54-3, that are anchored in, andextend horizontally or diagonally outwardly from, the shaft. Each of theprojections, 54-1, 54-2 and 54-3, has an abrasive nodule, 55-1, 55-2 and55-3, respectively, mounted at or near the end of the respectiveprojection. As the shaft 53 rotates, one or more of the abrasivenodules, 55-1, 55-2 and 55-3, is caused to move outward by centrifugalforce, to contact a burred surface and to thereby remove one or moreburrs from the burred surface. This contact may occur becausecentrifugal force exerted on the nodules by the shaft rotation causesone or more of the projections, 54-i (i=1, 2, 3), to bend so that acorresponding projection angle θ-i approaches 90° and the correspondingnodule 55-i moves as far as possible from the shaft 53 to which thenodule is attached. The tool 51 may include a motor or other shaftdriver mechanism 59 to rotate the shaft 53.

In any of the embodiments shown in FIGS. 1A, 1B, 4A, 4B, 5 and/or 6, theworkpiece having a burred surface may be rotated around a central axisindependently of whether or not the shaft and abrasive mechanism arerotated, for burr removal. Rotation of the workpiece may provide fasterand/or more uniform deburring of a burred surface.

The abrasive material used in an abrasive mechanism may be a high-carbonsteel, a metal impregnated with alumina or boron nitride or boroncarbide or diamond fragments, titanium, tungsten, a stiff wire brush, apolishing stone or any other suitable burr removal material.

The non-abrasive material used in a collar may be a plastic or othersacrificial material or may be a material with a Mohs hardness indexthat is below but near that of the metal from which burrs are to beremoved. Many metals have Mohs hardness indices of around 5.5 so that anon-abrasive material with a Mohs hardness index in the range 3-5 may besuitable.

FIGS. 7A and 7B illustrate a deburring tool 71 having a relativelyinflexible rotatable shaft portion 73-1, an abrasive mechanism 75, and arotatable flexible shaft portion 73-2 positioned between and connectedto the inflexible shaft portion and the abrasive mechanism. Preferably,the flexible shaft portion 73-2 is a flexible joint or spring that canmove laterally relative to the inflexible shaft axis AA, when the shaft73-1 is rotated with an angular velocity co, and thereby contact a sidewall 78 of a workpiece 79 from which one or more burrs is to be removed.A collar 77 of non-abrasive material extends laterally beyond theabrasive mechanism 75 to prevent the side wall 78 from scoring orgouging when the deburring tool 71 is being moved into place or is beingremoved from a region adjacent to the workpiece 79. As the inflexibleshaft portion 73-1 spins about its axis AA, the flexible joint 73-2 ismoved laterally by a centrifugal force, by a lateral distance that is atleast partly controlled by the angular velocity or spin speed ω of theinflexible shaft portion 73-1.

In another alternative for a deburring tool 81, illustrated in FIGS. 8Aand 8B, a rotatable inflexible shaft portion 83-1 may be positionedbetween a rotatable flexible shaft portion 83-2 and an abrasivemechanism 85 with collar 87 on a deburring tool 81 to deburr a sidewall88 of a workpiece 89. In any of the embodiments shown in FIGS. 7A, 7B,8A and 8B, the shaft may have a hollow core that partly or fullysurrounds the spring. shown in each of these figures. A shaft core mayinclude one, or more than one, spring. A shaft core may include aflexible shaft portion and a substantially inflexible shaft portion. Inany of the embodiments disclosed herein, a collar may be a substantiallysolid disk or may be a substantially annular disk.

In another alternative for a deburring tool 91, illustrated in FIGS. 9Aand 9B, a rotatable shaft 93 (preferably relatively inflexible) extendsfrom a rubber or other deformable shaft holder 92 at one end of theshaft to an abrasive mechanism 95 with a collar 97 at another end of theshaft 93. The deformable shaft holder 92 allows a longitudinal axis SSof the shaft 93 to become oriented in a direction that is notnecessarily parallel to an initial longitudinal axis AA of the shaft. Asthe deformable holder 92 is spun at an angular velocity co about theaxis AA, rotation of the substantial mass of the abrasive mechanism 95at the end of the shaft 93 will produce some asymmetry in the rotationposition of the abrasive mechanism, causing the shaft axis SS to differin direction and/or in its lateral location relative to the axis AA. Theabrasive mechanism 95 will “wobble” as it spins and will move closer toa side wall 98 of the workpiece 99 to provide deburring action.

When the shaft 93 and abrasive mechanism 95 are spun up for deburring,the shaft holder 92, whether deformable or otherwise, may develop acrack or fissure. The crack may propagate through and fragment the shaftholder and cause injury to the workpiece and/or to an operator of thetool 91. Optionally, the shaft holder 92 is provided with a cup, hood orsleeve 98, which may be rigid or deformable, that surrounds the shaftholder and/or shaft on several sides and catches or deflects any portionof the shaft or holder that might fragment and fly off. The cup, hood orsleeve 98 may extend to about the bottom of the shaft holder 92 or mayextend below the bottom of the shaft holder, as illustrated in FIGS. 9Aand 9B, respectively. A cup, hood or sleeve 98 may be provided for anyof the tool embodiments disclosed here.

In another alternative for a deburring tool 101, illustrated in FIG. 10,a workpiece 109 with side wall 108 rotates at a first angular velocityω1, and a rotatable shaft 103 with abrasive mechanism 105 and collar 107rotates at a second angular velocity ω2. Optionally, the workpiece 109and the abrasive mechanism 105 move in opposite circumferentialdirections (e.g., clockwise and counterclockwise, respectively) witharbitrarily chosen angular velocities, or move in the samecircumferential direction with different angular velocities (ω1≠ω2). Arotational axis SS for the shaft 105 is off-center relative to alongitudinal axis AA that serves as center of rotation for the workpiece109, and the abrasive mechanism 105 will “wobble” as the abrasivemechanism rotates and provide deburring action. In any of the FIGS. 1AB,4, 5, 6, 7AB, 8AB, 9AB, 10, 11AB, 12 and 14, the workpiece and thedeburring tool may rotate in opposite directions and/or at differentangular velocities.

In another alternative for a deburring tool 111, illustrated in FIGS.11A and 11B, a rotatable shaft 113 has at one end thereof a firstabrasive mechanism 115, a collar 117 and a second abrasive mechanism116, extending laterally as a plate of finite thickness or as acollection of abrasive projections. When the deburring tool 111 is movedto a first position, shown in FIG. 11A, the first abrasive mechanismprovides abrasive action on a side wall 118 of a workpiece 119. When thedeburring tool 111 is moved to a second position, shown in FIG. 11B, thesecond abrasive mechanism 116 provides abrasive action on the side wall118 of the workpiece 119. The first and second abrasive mechanisms, 115and 116, are preferably of different abrasive materials (e.g., for roughdeburring and for finishing, respectively) so that at least twodifferent deburring tasks can be performed without changing an abrasivemechanism or removing the deburring tool 111 from the workpiece 119.

FIGS. 12A, 12B and 12C are side views illustrating positioning and useof the invention when a rotating workpiece 129 is in a first angularposition. In FIG. 12A, the tool 120 is being moved longitudinally intoposition. A collar 127 of the tool contacts a surface of a workpiece 129and holds an abrasive mechanism 125 away from the surface. Because ofthis hold-off, a shaft 123, to which the abrasive mechanism 125 andcollar 127 are connected, is positioned at a non-zero angle θ_(sh)relative to an adjacent surface of the workpiece 129. This non-zeroangle θ_(sh) is achieved by application of a lateral force F_(L) thatbends or otherwise reorients a longitudinal axis of the shaft 123, whichis held by a drive mechanism and (flexible or rigid) shaft holder 128.As the tool 120 moves longitudinally, the collar 127 initially movesbeyond a corner C of the workpiece 129, and the angle θ_(sh) is reducedto a smaller, but non-zero, angle, as illustrated in FIG. 12B.

As the tool 120 moves further longitudinally, the abrasive mechanism 125makes contact with the corner C, and the angle θ_(sh) is reduced tosubstantially zero, as illustrated in FIG. 12C, and a side wall of theworkpiece 129 is directly exposed to the abrasive mechanism 125. In eachof FIGS. 12A, 12B and 12C, the workpiece 129 is in a first angularposition, and only a first aperture 129A in the workpiece 129 is shown.

In FIG. 12D, the rotating workpiece 129 has rotated to a second angularposition (approximately 90° from the first position). In this secondangular position, the workpiece 129 has an associated aperture 129B thatextends through at least part of the workpiece in a direction transverseto the plane of the FIGS. 12A, 12B and 12C. With the workpiece 129rotated to this second position, the abrasive mechanism 125 will need tore-orient itself in order to contact and remove a burr 121 that islocated within the second aperture 129B. In this situation, the shaft123 and abrasive mechanism 125 might be (re)introduced into the secondaperture 129B along an axis of this aperture, in order to contact andremove the burr 121.

Alternatively, in several; of the embodiments illustrated herein (e.g.,in FIGS. 1B, 7B, 8B, 9B, 10, 12A-12D, 16A-16B and 17B), the workpiececan be held against a movable table and the table can be caused torotate slowly while the abrasive mechanism of the deburring tool rotatesmore quickly in the same direction or in an opposiate direction. Thisapproach will cause a workpiece that has a vertical first aperture and ahorizontal second aperture to move as illustrated, for example, in FIGS.12A-12D.

In another alternative for a deburring tool 131, illustrated in FIG. 13,the axis AM-AM of an abrasive mechanism 135, which extends laterallyfrom a rotatable shaft 133, can be rotated by an arbitrary anglerelative to a longitudinal axis AA. By rotating the axis AM-AM, and thuschanging the angular orientation of the abrasive mechanism 135 by anangle θ, the abrasive mechanism can be oriented as shown to remove burrson a rounded or polygonal corner C of a side wall 138 of a workpiece139. The material used in the abrasive mechanism 135 can be a relativelyhard abrasive for rough deburring or can be a relatively soft abrasivefor surface finishing. Optionally, the abrasive mechanism 135 includesone, two or more non-abrasive collars, 137A and 137B, to protect theside wall 138 as the deburring tool 131 is mover into position or isremoved from the workpiece 139.

Preferably, the shaft 143 includes a superelastic shaft core 143-1 thateasily bends into an arc and continues to rotate about its (now-curved)axis S′S′, as illustrated in FIG. 14. The shaft 143 also includes: apartly flexible shaft guide sleeve 143-2 that covers most of, and maybut need not rotate with, the shaft core 143-1; and an inflexible guidesleeve 143-3 that covers part of the shaft guide sleeve 143-2 and doesnot rotate.

In FIG. 13, the cross-sectional shape of the abrasive mechanism 135 iscurvilinear and concave, to more easily abrade a rounded corner on aside wall 138. In an alternative embodiment of a deburring tool 151,illustrated in FIG. 15, the cross-sectional shape of the abrasivemechanism 155 is concave and has at least one linear segment (or ispolygonal), with geometric parameters that enable the abrasive mechanism155 to remove burrs on a sharply angled polygonal corner C′ (e.g., aright angle corner) by rotation of the shaft axis S′S′ relative to aninitial longitudinal axis for the tool.

In the systems 161 and 161′ illustrated in FIGS. 16A and 16B, thecross-sectional shape of the abrasive mechanism is convex curvilinear orovular (165 in FIG. 16A) and convex polygonal (165′ in FIG. 16B),respectively. The convex curvilinear cross-sectional shape shown in FIG.16A is best suited for removing burrs and other unwanted material from acorner C on a curved convex surface, as illustrated, having a localradius of curvature that is at least as large as the radius of curvatureof the abrasive mechanism. The convex polygonal cross-sectional shape(including, but not limited to, triangular and quadrilateral) shown inFIG. 165B is best suited for removing burrs and other unwanted materialfrom a corner C′ on a relatively flat or polygonal shape local surface,as illustrated, where the abrasive mechanism surface can be orientedapproximately parallel to the local surface and thus avoid or minimizeremoval of material other than burrs.

As illustrated by the system 171 shown in FIGS. 17A and 17B, an abrasivemechanism 175 with a curvilinear shape on a deburring tool 171 can bepositioned and operated to convert a corner C having a polygonalcross-sectional shape on a side wall 178 (FIG. 17A) into a corner C′having a curvilinear cross-sectional shape (FIG. 17B). Using an abrasivemechanism with a polygonal shape, such as 165′, shown in FIG. 16B, onecan convert a corner C′ (FIG. 17B) into a corner C (FIG. 17A).

Side and end views in FIGS. 18A, 18B and 18C illustrate use of a shaftrestrictor 181 to restrict motion of a shaft 182 in any lateraldirection as the shaft turns and the abrasive mechanism 183 encountersmechanical resistance. Two spaced apart locations, 182A and 182B, of theshaft are received by corresponding aligned apertures, 184A and 184B, ina first curved or shaped plate 185. Preferably, the first plate 185 isconnected or rigidly attached to a shaft driver mechanism 186 (e.g., amotor), or to some other relatively rigid device, by a second plate oranchor 187 so that the first plate 185 does not move relative to theshaft drive mechanism 186 as the shaft 182 turns within the apertures,184A and 184B. Presence of the two aligned apertures, 184A and 184B,surrounding the shaft 182 at spaced apart locations helps to ensure thatthe shaft itself is aligned and moves at most a minimal lateral distanceas the shaft rotates. Preferably, the aperture diameters, d(l84A) andd(l84B), are slightly larger than the shaft diameter d(182). Optionally,the aperture diameter d(184A) differs slightly from the aperturediameter d(184B), in order to more accurately align the shaft 182 withinthe apertures, 184A and 184B.

The plate 185 and apertures, 184A and 184B, in FIG. 18A can be replacedby, or supplemented by, two spaced apart collars, 188A and 188B, thatalign, and restrict the lateral motion of, the shaft 182, as illustratedin FIG. 18D.

The end view in FIG. 18B (or 18C) illustrates a shaft restrictor 181 torestrict motion of the shaft 182 in any lateral direction as the shaftturns, using the first plate 185 with a single aperture (184A or 184B),where the first plate is preferably connected or rigidly attached to theshaft drive mechanism 186 by the second plate or anchor 187. Use of ashaft restrictor 181 with a single aperture does not align the shaft 182as well as the shaft restictor 181 aligns the shaft, but in otherrespects the single-aperture and two-aperture shaft restrictors performsimilarly.

In FIG. 19, a shaft restrictor 191 includes a plate 195 with an aperture194 that restricts motion of a shaft 192 in one lateral direction (x)but permits motion of the shaft in a second lateral direction (y). Theshaft restrictor 191 shown in FIG. 19 will be useful where an abrasivemechanism and shaft must move in one lateral direction to follow thecontours of the workpiece to be deburred.

FIGS. 20A, 20B and 21 are end and side views illustrating an arrangementthat incorporates some of the invention's features in a milling machineor lathe, for example, as a retrofit arrangement. FIGS. 20A and 20B areend views of a rotation machine 201, such as a lathe or milling machine,that has a rotatable base 202 having a longitudinal central axis 203 andhaving one or more apertures 204-j (=1 . . . , J; J≧1) formed in thebase. One or more of the apertures 194-j has a subsidiary rotationmechanism 205-j positioned therein that provides independent rotation ofa shaft 206-j. The subsidiary rotation mechanism 205-j can serve as ashaft drive mechanism for a burr removal system, such as the systemshaft drive mechanism 19 shown in FIGS. 1A and 1B. For example, therotatable base 202 can rotate about its axis 203 in a clockwisedirection, and the subsidiary rotation mechanism 205-j can independentlyrotate the shaft 206-j in a clockwise or counterclockwise direction, asillustrated in FIG. 20A. Alternatively, the shaft 206-j can be heldstationary so that only the rotatable base 202 rotates, as illustratedin FIG. 20B.

FIG. 21 is a side view illustrating a subsidiary rotation mechanism205-j that is connected to an abrasive mechanism 207-j and associatedcollar 208-j through a rotatable shaft 206-j. Preferably, the shaft206-j is controllably moved longitudinally, in a direction parallel toan axis BB, to position the abrasive mechanism 207-j relative to theworkpiece (not shown). Optionally, the shaft 206-j includes a flywheelor other similar rotatable mass 210-j that provides a rotational inertiastorage mechanism. The subsidiary rotation mechanism 205-j is activatedand spins up the shaft 206-j, the abrasive mechanism 207-j and theassociated collar 208-j to an appropriate angular velocity ω0. The shaft206-j, the abrasive mechanism 207-j and the associated collar 208-j arethen optionally moved longitudinally parallel to the axis of the shaft206-j until the abrasive mechanism engages a portion of the work surfaceto be deburred. The subsidiary rotation mechanism 205-j may continue inits activated state to rotate the shaft 206-j, the abrasive mechanism207-j and collar 208-j. Alternatively, the subsidiary rotation mechanism205-j is deactivated or turned off; and the shaft 206-j, the abrasivemechanism 207-j and the associated collar 208-j are allowed to continueto rotate at an angular velocity ω that slowly decreases from itsinitial value ω0, due to internal friction and due to frictionencountered by the abrasive mechanism 207-j as one or more burrs isremoved. Inclusion of the rotatable mass 210-j on the shaft 206-jprovides additional rotational inertia (≈I•ω², where I is the moment ofinertia of the rotatable mass alone) that helps to sustain the angularvelocity ω near its initial value ω0 in the presence of friction.

Each embodiment of the invention incorporates one or more of thefollowing features: (1) provision of a non-abrasive collar, combinedwith an adjacent abrasive mechanism, to protect a surface fromunintended abrasion when the system is being moved into position toremove one or more burrs; (2) provision of an abrasive mechanism havinga cross-sectional shape that corresponds to the local shape of thesurface from which one or more burrs is to be removed; (3) provision ofa bendable shaft that can be mechanically loaded or bent to provide anabrasive mechanism with a directed force against a surface from whichone or more burrs is to be removed; (4) provision of a shaft restrictorthat restricts shaft motion in one or more lateral directions when theabrasive mechanism is rotating; and (5) use of rotational inertiastorage to sustain rotation of the shaft(s), abrasive mechanism(s) andcollar(s) after the shaft drive mechanism is turned off and the angularvelocity decreases slowly due to frictional forces.

1. Apparatus for removing a burr from an aperture in a workpiece, theapparatus comprising: a flexible shaft that can be rotated about a shaftaxis, having a shaft first end, at a selected angular velocity; anapproximately cylindrically symmetric abrasive mechanism, connected to alocation near a first end of the shaft and including an abrasivematerial that can abrade a selected section of a workpiece that iscontacted by the mechanism; a collar of a selected material that willnot substantially abrade the workpiece when the workpiece is contactedby the collar, the collar being connected to the abrasive mechanism; andwhereby, when the abrasive mechanism, the collar and at least a portionof the shaft are inserted into an aperture in the workpiece and theshaft is rotated, at least one workpiece burr in the aperture can beremoved by contact of the abrasive mechanism with the at least one burr.2. The apparatus of claim 1, wherein said abrasive mechanism hassubstantially a cross-sectional shape drawn from a group consisting of aportion of an ovaloid, a portion of a triangle a portion of aquadrilateral, and a portion of a polygon.
 3. The apparatus of claim 1,wherein said collar material is drawn from a group of non-abrasivematerials consisting of wood, plastic rubber and soft metal.
 4. Theapparatus of claim 1, wherein said material for said abrasive mechanismis drawn from a group of abrasive materials consisting of boron nitride,boron carbide, tungsten carbide, alumina, high carbon steel, and a metalimpregnated with at least one of alumina, boron nitride, boron carbide,tungsten carbide, diamond fragments, titanium and tungsten.
 5. Theapparatus of claim 1, wherein said shaft has a hollow shaft core.
 6. Theapparatus of claim 5, further comprising a spring, located in saidhollow core, that contacts said shaft at at least one location withinsaid hollow core.
 7. The apparatus of claim 5, wherein said shaft canflex or bend in a selected direction in response to force on said shaftin the selected direction.
 8. The apparatus of claim 1, wherein saidcollar is located at a first end of said abrasive mechanism that isspaced apart from said first end of said shaft.
 9. The apparatus ofclaim 1, wherein said collar is located at a first end of said abrasivemechanism that is adjacent to said first end of said shaft.
 10. Theapparatus of claim 1, wherein said shaft comprises a spring mechanismlocated adjacent to said first end of said shaft.
 11. The apparatus ofclaim 1, wherein said shaft comprises a spring mechanism that is spacedapart from said first end of said shaft.
 12. The apparatus of claim 11,wherein said shaft said spring mechanism is located adjacent to a secondend of said shaft.
 13. The apparatus of claim 1, wherein said shaftcomprises a deformable body of material that holds a second end of saidshaft and allows said shaft axis to vary.
 14. The apparatus of claim 1,wherein said shaft comprises a first shaft section that is substantiallyinflexible and a second shaft section, connected to said first shaftsection, that is flexible and can be moved laterally as said shaftrotates.
 15. The apparatus of claim 14, wherein said first shaft sectionis adjacent to said abrasive mechanism.
 16. The apparatus of claim 14,wherein said second shaft section is adjacent to said abrasivemechanism.
 17. The apparatus of claim 1, further comprising a shaftholder, connected to said shaft at a second shaft end, that permits saidabrasive mechanism to move laterally when said shaft and said abrasivemechanism rotate.
 18. The apparatus of claim 17, further comprising asleeve that is adjacent to said at least one of said shaft and saidshaft holder and that is positioned to catch or deflect at least onefragment of said shaft holder.
 19. The apparatus of claim 1, whereinsaid workpiece has a workpiece axis, and said workpiece rotates aboutthe workpiece axis at a selected second angular velocity in a firstselected circumferential direction.
 20. The apparatus of claim 19,wherein said shaft rotates about said shaft axis at said first selectedangular velocity in a second selected circumferential direction.
 21. Theapparatus of claim 20, wherein said first and second circumferentialdirections are oppositely oriented.
 22. The apparatus of claim 20,wherein said first and second circumferential directions are the sameand said first and second angular velocities differ from each other. 23.The apparatus of claim 1, wherein: said shaft has a superelastic shaftcore that elastically bends easily into an arc, a partly flexible shaftguide sleeve that surrounds a selected part of the shaft core and allowsthe shaft core to bend, and a substantially inflexible guide sleeve thatsurrounds a selected part of the flexible shaft guide sleeve; and saidabrasive mechanism has a cross-sectional shape, viewed alongperpendicular to shaft axis, that is at least partly curvilinear. 24.The apparatus of claim 1, wherein: said shaft has a superelastic shaftcore that elastically bends easily into an arc, a partly flexible shaftguide sleeve that surrounds a selected part of the shaft core and allowsthe shaft core to bend, and a substantially inflexible guide sleeve thatsurrounds a selected part of the flexible shaft guide sleeve; and saidabrasive mechanism has a cross-sectional shape, viewed alongperpendicular to shaft axis, that is at least partly linear.
 25. Theapparatus of claim 1, further comprising: a second approximatelycylindrically symmetric, abrasive mechanism, rigidly connected to atleast one of said shaft and said first collar and located adjacent tosaid first collar and including a second abrasive material that canabrade said workpiece that is contacted by the second mechanism;whereby, when the second abrasive mechanism and at least a portion ofthe shaft are inserted into an aperture in said workpiece and said shaftis rotated, at least one workpiece burr in the aperture can be removedby contact of the second abrasive mechanism with the at least one burr.26. The apparatus of claim 25, further comprising: a second collar of asecond selected material that will not abrade said workpiece whencontacted by the second collar, the second collar being rigidly attachedto at least one of said shaft and said second abrasive mechanism andlocated adjacent to said second abrasive mechanism.
 27. The apparatus ofclaim 25, wherein said second abrasive material is chosen to besubstantially less abrasive than said first abrasive material.
 28. Theapparatus of claim 25, wherein said second abrasive material is chosento be substantially more abrasive than said first abrasive material. 29.The apparatus of claim 25, wherein said first abrasive mechanism andsaid second abrasive mechanism are attached to said collar on oppositesides of said collar.
 30. The apparatus of claim 1, wherein said collaris a substantially solid disk.
 31. The apparatus of claim 1, whereinsaid collar is an annular mechanism.
 32. The apparatus of claim 1,further comprising a shaft restrictor mechanism comprising a shaftreceptor plate, having a selected shape and having at least one aperturetherein to receive, and allow passage therethrough of, said shaft, andto allow said shaft to rotate in the at least one aperture in asubstantially fixed position relative to the shaft receptor plate. 33.The apparatus of claim 32, wherein said shaft receptor plate has atleast two of said apertures, spaced apart and aligned to receive, andallow passage therethrough of, said shaft at the same time.
 34. Theapparatus of claim 33, further comprising a shaft driver mechanism,connected to cause said shaft to rotate approximately about said shaftaxis.
 35. The apparatus of claim 34, wherein said shaft receptor plateis connected to said shaft driver mechanism.
 36. The apparatus of claim1, further comprising a shaft driver mechanism, connected to said shaftto cause said shaft to rotate approximately about said shaft axis. 37.The apparatus of claim 36, further comprising a rotatable mass,connected to said shaft, to provide a selected amount of additionalrotational inertia when said shaft is rotated.
 38. The apparatus ofclaim 37, wherein said shaft driver mechanism is activated to rotatesaid shaft and said rotatable mass at a selected initial angularvelocity ω0, whereby, when said shaft driver mechanism is subsequentlydeactivated, the angular velocity of said shaft and said rotatable massdecreases slowly below the initial value ω0 primarily due to frictionalforces.
 39. A method for removing a burr from an aperture in aworkpiece, the method comprising: providing a flexible shaft that can berotated about a shaft axis, having a shaft first end, at a selectedangular velocity; providing an approximately cylindrically symmetricabrasive mechanism, connected to a location near a first end of theshaft and including an abrasive material that can abrade a selectedsection of a workpiece that is contacted by the mechanism; providing acollar of a selected material that will not substantially abrade theworkpiece when the workpiece is contacted by the collar, the collarbeing connected to the abrasive mechanism; and whereby, when theabrasive mechanism, the collar and at least a portion of the shaft areinserted into an aperture in the workpiece and the shaft is rotated, atleast one workpiece burr in the aperture can be removed by contact ofthe abrasive mechanism with the at least one burr.
 40. The method ofclaim 39, further comprising providing a shaft driver mechanism,connected to said shaft, to cause said shaft to rotate about said shaftaxis at said selected angular velocity.
 41. The method of claim 40,further comprising providing a rotatable mass, connected to said shaft,to provide a selected amount of additional rotational inertia when saidshaft is rotated.
 42. The method of claim 41, further comprising:activating said shaft driver mechanism to rotate said shaft at aselected initial angular velocity; and deactivting said shaft drivermechanism and allowing the angular velocity of said shaft to slowlydecrease in response to frictional forces encountered by at least one ofsaid shaft, said abrasive mechanism and said collar.
 43. The method ofclaim 39, further comprising providing a lateral force in a selecteddirection against said shaft to force said abrasive mechanism to contacta selected portion of said workpiece in said aperture.